why does Windows 7 x64 Explorer.exe suddenly gobble up all available RAM and slow my system to a crawl?

Question

UPDATE: RESOLVED - see my answer below

Frequently, while I'm navigating through folders in a Windows Explorer window (Explorer.exe, not to be confused with Internet Explorer), suddenly I'll hear my hard disk start to thrash and my system becomes unresponsive. When I manage to get Task Manager open (Control-Alt-Delete -> Start Task Manager), I can see that Explorer.exe is using rapidly increasing amounts of RAM, from 1.5GB to 2GB and up. If I watch the RAM numbers for a few seconds, Explorer.exe will go up to about 4GB and then it zeros out and starts over. All the while, my hard disk is thrashing and I can't do anything with my computer. I have managed to get back to normal by terminating the Explorer.exe process and then using Task Manager's Run... command to restart Explorer.exe. These episodes keep my system unusable for anywhere from 3 to 5 minutes.

I have been told that this is a virtual memory problem. My virtual memory settings are fine -- they're set to automatic. I have around 10% free space on all of my hard disks.

I tested system files with sfc /scannow and found no problems.

I tested my RAM using Windows Memory Diagnostic and found no problems.

I've noticed the problem occurs specifically when browsing through folders in the Documents library. It happens almost every time I navigate through my frequently used folders, especially if I move through the folders quickly. It often happens when I'm attempting to open Word files.

The system will "freak out," usually for about 2 or 3 minutes. When I'm able to see the RAM usage during the system, it is up at around 98% or even higher.

One possible complication is that I moved the Document Library locations to a different disk (F:), not the same disk that Windows is installed on (C:), but this shouldn't be a problem.

Any ideas?

NEW DETAILS 9/10/11:

I am now experiencing this problem on two different Windows 7 x64 computers. Exactly the same problem occurs on both, with explorer.exe gobbling up all available RAM and slowing the system to a crawl. I believe the following procedure will trigger the problem.

1) Navigate to a folder synchronized with Windows Live Mesh 2011 that contains at least two Word document files.

2) Click (do not double click) one of the Word document files. Then click a different Word document file. Repeat this several times.

3) Perform a file operation. (Delete, copy, or open one of the Word files.)

4) The system will seem to slow down or "freeze" temporarily. If you look at Task Manager, up to 99% or even 100% of RAM will be in use. The explorer.exe process will use rapidly increasing amounts of RAM.

I am more convinced than ever that Windows Live Mesh 2011 is the culprit here. I will uninstall this program and re-test both systems, then update this question with more information. If you have any further insights, please help. Thank you.

Based on excellent suggestions from Superuser, I've done a lot of troubleshooting. Currently, I have mitigated the problem, but I still haven't eliminated it. After clearing the Windows thumbnail cache, the RAM spike and hard disk thrashing I describe above still happens, but the duration of the attack is only about 5 or 10 seconds now (instead of 3 or 5 minutes). Another step that helped was selecting "Launch folder windows in a separate process" in Explorer's Folder Options, on the View tab. This has isolated the troubled window, so that when I need to terminate explorer.exe, my taskbar and desktop aren't usually affected.

Answer 1

Try running Process Monitor or Process Explorer and capture what happens during "normal" operation as well as during the moments when it seems to slow down. That's a way of troubleshooting it.

You could also try uninstalling Live Mesh and see if it makes a difference.

Answer 2

Try clearing your thumbnail cache, use disk cleanup to do this.

Also if you have image or especially video files in some of those folders that Windows is unable to generate thumbnails for because it does not have the codec needed, this can cause Explorer issues, slow downs or even crashes.

If you can locate the folders with files that Windows cannot generate a thumbnail for, change the view setting for that folder to something like details, so it will not attempt to generate thumbnails.

If they are MKV video files see this thread

Answer 3

The problem stems from a memory leak in explorer.exe when it attempts to show file image previews (thumbnails) of Word 2007 files.

I solved the problem by preventing explorer.exe from showing these file image previews. To do so, I edited the Windows registry.

Be careful when editing the registry - if you make a mistake it could cripple your computer. Always back up your registry first, by following these instructions.

To edit the registry:

1. Click Start and type "regedit.exe." A shortcut to Regedit.exe will appear.
2. Right-click the shortcut to Regedit, and select "Run as administrator." Provide credentials if necessary.
3. In Regedit, navigate through the folders listed on the left to the following location:

HKEY_CLASSES_ROOT.dotx\ShellEx{BB2E617C-0920-11d1-9A0B-00C04FC2D6C1}

4. Click on the word "default," and confirm that the value listed is: "{C41662BB-1FA0-4CE0-8DC5-9B7F8279FF97}". (If you see a different value, redo the previous step to make sure you're at the right location in the registry).

5. Then press the "Delete" key on your keyboard. Confirm the deletion.

6. Repeat steps 3. and 4. for the following location:

   HKEY_LOCAL_MACHINE\SOFTWARE\Classes.docx\ShellEx{BB2E617C-0920-11d1-9A0B-00C04FC2D6C1}

   "default" value: "{C41662BB-1FA0-4CE0-8DC5-9B7F8279FF97}"

More information is available here.

Answer 4

I recently discovered that the Windows feature Offline Files can cause the sorts of errors described in this question. I disabled Offline Files about one week ago. I haven't experienced the system instability I described in the question since disabling Offline Files.

To disable Offline Files in Windows 7 (should be the same for Vista):

1. Click Start and search for "Offline Files." Click "Manage Offline Files."

2. Click "Disable Offline Files."

Answer 5

Unless there is something instable at a lower level, shell extensions are the main culprit.

Use ShellExView to disable those that are not by Microsoft, you can try re-adding the ones you after...

Answer 6

The problem might be the search indexing in Windows 7.

The article Disable Search Indexing In Windows 7 shows how to disable it definitively, and explains :

In order to speed up the search process, the Search indexing service scans through the files and folders on the Windows system and records information about them in an index file. But it also consumes some resources of the system, so for the users with a slow computer it is beneficial to turn off search indexing.

You might try first to disable this service, as explained in the article, to see if this is the problem. If it is not, then re-enable it. If it is, then keep reading below.

More information can be found in Improve Windows searches using the index: frequently asked questions :

Indexed locations include all folders included in libraries (anything you see in the Documents library, for example), e‑mail, and offline files. Files that aren't indexed include program files and system files—files that most people rarely need to search.

The problem in this case might be that your libraries include very many files that the Indexer requires too much memory to index. Maybe this is just a simple bug with one particular document that it keeps looping on. You could use the information in the second article section "How do I add or remove index locations" to reduce the number of folders that are being indexed until you find the problematical library.